Historically, cartridge or plug-in pumps have been employed in those environments where the pump is housed within the confines of a tank or receptacle containing fluid to be delivered under pressure remote from the tank or receptacle. These cartridge or plug-in pumps, as they are frequently called, are so designed as to permit their ready removal from the tank or receptacle for replacement or repair. The pumps may be primary sources of fluid under pressure, or they may function as boost pumps to deliver the fluid from the tank or receptacle to another pump for final delivery to a system end use.
In an aircraft environment these pumps are located on the bottom surface of the fuel tanks to allow access from below, as well as ensure that all fuel resting on the bottom of the tank is drawn off by the pump for its ultimate intended use.
The fuel tanks may be at varying levels of fullness and the removal of the pump must be effected without the requirement of draining the fuel tank. A number of inventions have recognized the basic problem of pump removal with a concomitant need for sealing off the fuel tank from the pump housing to allow pump removal without the requirement of first draining the fuel tank.
The Paul U.S. Pat. No. 3,000,543 provides a plug-in pump assembly which has a pump and motor "D" surrounded by a slideable sleeve 26 which sleeve 26 has an opening 47 that allows fuel from a tank "T" to pass into a pump inlet 12 of the pump and motor combination "D." The sleeve 26 is secured for sliding movement with the pump and motor "D," such that the sleeve 26 and its opening are moved to a position where the housing of the fuel tank obstructs the flow of fuel from the tank "T" to the pump and motor "D." Subsequent rotation and then downward movement of the pump and motor "D" allow for its removal.
In the Howard et al U.S. Pat. No. 3,539,272, there is disclosed a rotatable valve member 66 provided for closing off a fuel passage or inlet 46 from a fuel tank 10 prior to withdrawal of a pump and motor assembly 30. The valve member 66 is manually rotatable after removal of a closure plate 130 covering the pump end of the pump and motor assembly 30.
Inherent in both of these patents is the need for some sequential steps in the removal of a pump to assure that removal of the pump will not inadvertently allow the fuel in the tank to escape through the tank opening in which the pump is removed. The prior art does not include any means to insure that a valve which closes off a fuel passage to the pump is locked in place prior to removal of the pump. In addition, the prior art makes no provision to preclude fuel pump drainage, until a valve which closes a fuel passage to the pump is locked in place.
The invention to be described more fully hereinafter provides an even greater measure of security than the apparatus of the prior art in a simple yet expeditious manner.